The nation's second-largest health insurance company has officially changed its corporate name from WellPoint Inc. to Anthem Inc. The Indianapolis-based insurer's stock starts trading Wednesday under the ticker symbol ANTM.

The insurer will not let customers who renewed their pre-Obamacare plans late in 2013 do so again this year. But switching to Obamacare-compliant plans could cause some premiums to spike and provider choice to dwindle.